An X-Ray CT Validated Laboratory Measurement Method for Air Voids Distribution Over Depth in Asphalt Pavement: A Step Toward Simplified Oxidation Modeling

Abstract

Recent efforts relating pavement failure to binder hardening have resulted in a pavement oxidation model. A key parameter, the diffusion depth, the ratio of binder volume to accessible air void surface area, is determined via X-ray computed tomography (CT). Toward an alternative determination, in this work volumetric techniques were employed to measure total air voids of core slices over the pavement depth. Because the 0.4-inch-thick slices are insufficient to meet standard method specimen size requirements, precision was evaluated and alternative maximum theoretical specific gravity methods were compared. A vacuum dryer increases efficiency without oxidizing the binder. Air void distributions compare favorably with X-ray CT measurements.

Evolution of dynamic flow behavior in asphalt mixtures exposed to freeze-thaw cycles

“…This technique is based on the X-ray spectrometer to image the internal microscale structure of objects without destruction. To date, however, in the asphalt mixture studies at microscale, the X-ray CT was mainly dedicated to the characterization of pore structure of particular samples or to monitor structure evolution under various external factors [26][27][28]. X-ray CT is less extensively used as a nondestructive approach to image the inner structure of asphalt mixtures, combining moisture, aggregate, and voids.…”